This follows a couple rough days for the peso, which tumbled after an earlier poll had Trump in the lead.

"What has unsettled the markets is not that there are two flawed candidates. Rather investors had grown comfortable with the idea that Clinton was going to win, and last week's announcement by the FBI has made them doubt this," Marc Chandler, the global head of currency strategy for Brown Brothers Harriman, wrote.

"Investors know that regardless of their personal feelings, Clinton is a known quantity. Trump simply is not. This is not a slight. Agents of change are by definition more hostile to longstanding practices that have become a tradition," he added.

Zooming out to look at the bigger picture, it's notable that politics has become a greater player in markets over the last year. While it's not wholly unexpected to see market moves with respect to political turmoil in emerging markets given long-run structural issues, it's notable that this year we've seen markets reacting to an increasing number of "unknown" political developments in developed markets — for example, with the US presidential election and Brexit.

"The separation of politics and economics is taken for granted by many, and that makes this current period so frustrating," Chandler wrote. "Investors, perhaps like many voters, just want to get the US election over with already. And yet this is a democratic moment, for all its warts and frailties and flaws. "

As for the rest of the world, here's the scoreboard as of 11:59 a.m. ET:

The British pound surged by 1.2% at 1.2456 against the dollar after the High Court ruled that the British government cannot begin the formal process to leave the European Union without first having a vote in parliament. Separately, the Bank of England held rates at its record low of 0.25%.

The Egyptian pound was floated. The country's central bank devalued the currency by 32.3% to 13 per dollar. It was previously pegged at 8.8 per dollar since March.

The US dollar index is little changed at 97.27 after Markit services purchasing managers index and ISM non-manufacturing index came in solidly in growth territory, albeit with mixed results against expectations. Separately, f actory orders rose by 0.3% in September month-over-month, above expectations.

The Russian ruble is down by 0.3% at 63.7233 per dollar, while Brent crude oil, the international benchmark, is down by 0.4% at $46.66 per barrel.